The basic RNA components of the Kirsten and Harvey murine sarcoma virus genomes have been identified as (1) type-C leukemia virus RNA sequences recombined with (2) specific rat cellular RNA sequences. We have found that removal of oxygen from normal, uninfected rat cells triggers a massive induction of these same RNA sequences. Work for the coming year will be particularly directed at clarifying this induction response in normal cells, with the objective of defining the cellular controls of these potentially oncogenic RNA sequences. Diverse agents will be examined for their ability to block the induction responses, and detailed kinetic studies will also be performed. Tumor-derived and virus transformed rat cells will be compared and contrasted with normal cells as to the controls, structure and possible functions for the two types of RNA sequences.